Natural wood rail and metal pipe fencing is the fastest growing type of fence in the United States. Many consider this type of fencing to be more attractive than hurricane type fencing because it combines the strength and durability of metal pipe with the privacy of a wooden pickets which can be painted or stained to suit an owner's preferences. While some fences are still built with wood fence posts, the resistance of metal pipe to termites and wet rot commends its use anywhere in the country, and especially in regions such as the south having soil with high clay content. Basically, horizontal wooden rails are connected to a galvanized fence pipe by fence pipe brackets that are affixed to the pipe. These brackets have a semi-circular portion that engages a fence pipe and possess a pair of adjacent flanges for the attachment of rail ends. The terms “post” or “pipe” as used herein are intended to refer to metal pipe-type fence posts.
Prior to attaching brackets and rails to a fence pipe, it is necessary install the pipe, typically by digging post holes and filling around the pipe base with wet concrete. Shortly after the concrete is poured at the pipe base, it is necessary to plumb the fence pipe with some kind of tool. The use of vial levels at right angles to plumb the pipe can be traced at least back to U.S. Utility Pat. No. 312,266 issued to Gurley. The Gurley device and its structural descendants have a right angle configuration—basically two planar sections; e.g., “flaps” joined at their midpoint that permits attachment to either square or round posts via a rubberband, chain or strap placed around the post, or a magnet. Currently, devices similar to the one described in U.S. Pat. No. 5,207,004 to Gruetzmacher are sold as post levels that permit plumbing of the post by comparing two horizontal bubble vials positioned at 90 degrees relative to one another with a third bubble vial positioned at a right angle to the horizontal vials. While these types of devices are popular, and function for both round and square posts, they are cumbersome tools where one has to coordinate and “match” the bubbles in the separate vials to obtain vertical. Although with practice, good results can be obtained, one must spend sufficient time getting a “feel” for the tool in order to work efficiently. Obviously, a hand held torpedo level, for example, may be employed in a similar fashion.
Because of the void occurring in the mid line where the two flaps meet, magnet placement and magnet position is also restricted to a very narrow area on the adjacent flaps so that it will contact the fence pipe. Accordingly, the regions on the flaps directly contacting the fence pipe surface are relatively limited in total area which often leads to the device shifting out of longitudinal alignment relative to the fence pipe. Even though some of the foregoing devices include magnets, the magnets are typically flexible-type magnets with poor attractive properties which are frequently not strong enough to secure the particular device to the fence pipe. The surfaces of such magnets wear quickly when used on galvanized fence pipe, due to the fence pipe coating abrading the substrate impregnated with magnetic particles—typically a rubber material.
A bulls-eye spirit level, also known as a “target” level or “orbital” level allows for simultaneous leveling in two axes with a single bubble. Bulls-eye type spirit levels are used commonly to plumb surveying instruments and camera tripods. Other post alignment devices using bulls-eye levels instead of vial levels have been described in the past; e.g., U.S. Pat. No. 3,826,013 to Baher, U.S. Pat. No. 4,343,093 to Eadens, U.S. Pat. No. 5,174,034 to Swanda, U.S. Pat. No. 5,408,752 to Eadens, and U.S. Pat. No. 5,839,200 to Decesare. While the foregoing devices utilizing bulls-eye levels offer certain advantages over two vial levels placed at right angles, use can be difficult requiring one hand to hold the plumbing tool and one hand to maneuver the post. In addition, like the right angle devices mentioned previously, the foregoing devices contact the fence pipe via two thin longitudinal strips which can lead to inaccuracies in cases where the galvanized coating is rough. Furthermore, care must be taken to ensure that the devices do not shift out of place; i.e., out of longitudinal alignment with the pipe, due to the reduced surface contacting areas. In cases where the device is mounted to a post by a rubber band, strap or chain, it still takes two hands to mount and dismount the device. One salient issue unaddressed by past devices is that of unintentional movement imparted to the post when dismounting a plumbing device from a post. For devices held on with a strap or chain, care and a light touch must be employed when removing the device, or the post will slightly shift out of plumb shifting in the wet concrete. It is very difficult to maintain the post or fence pipe sitting in wet concrete in sufficient plumb when removing one of the past devices. Re-plumbing the fence pipe after the concrete has partially set can lead to a loose fit at the fence pipe base.
For purposes of plumbing a fence pipe, it would be desirable to provide a small, lightweight device capable of being carried in a shirt or pants pocket, while having the advantages of a spirit level and a mounting means that provides for both low force; i.e., low movement, mounting and dismounting to a pipe.
It would be especially desirable if the low force mounting means for the pipe alignment device is sufficient to prevent detachment, slipping or shifting of the plumb device on the pipe, yet still possessing a magnetic attachment means having a relatively high pull force (herein provided in lbs and kg pull force) within a relatively small contact region, such that the device is readily attached to the pipe, easily dismounted, and wherein the pipe is not inadvertently pulled out of alignment either when mounting or dismounting.
It would be further desirable if the device required no actual manual placement of the device directly to a fence pipe when mounting the pipe, the mounting of the device accomplished by positioning the device near enough to the metal fence pipe, such that it actually magnetically jumps from the fingers to the fence pipe, attaching and self aligning itself.
It would be still further desirable if the device were to be removable from the fence pipe by simply pulling it free by tipping the device up or down without disturbing the orientation of the fence pipe.